JPH0151227B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD This invention relates to telephone subscriber loop test systems. It is known that multiple subscriber channels can be provided with fewer metal wire pairs by using conventional analog or digital carrier techniques. A typical analog carrier system is shown in US Pat. No. 4,196,321 to B.S. Boszczuk. A digital subscriber loop carrier system is shown in US Pat. No. 3,963,869 to G. L. Caldwell, dated June 15, 1976. Various techniques are known for testing the carrier portion of these carrier systems. For example, the aforementioned B.S. Bosick patent and the January 1977 patent.
G.E. Dale U.S. Patent No. 11, dated
No. 4002847. However, such a system has not only a channel formed by the carrier, but also an audio frequency drop-in line from the remote carrier terminal to the subscriber served by it. It is desirable to test both the channel formed by the carrier for a particular subscriber and the voice frequency drop-in line for that subscriber. According to the invention, a channel formed by a carrier in at least one subscriber line pair multiplexing system, i.e. a gain-pair subscriber loop transmission system;
A system is provided for testing a subscriber loop formed by a combination of local drop lines from a remote terminal of the transmission system to a subscriber telephone set;
The test system includes drop-in test means for extending a metal wire signal path from a central office test facility to a local drop-in of the subscriber being tested, and a channel formed by a carrier corresponding to said subscriber being tested. It consists of a channel test means to test. Here, a gain-to-gain subscriber loop system is a subscriber telephone device that multiplexes multiple subscriber line pairs onto a multiplex transmission path to improve the utilization of telephone cables, and is similar to a digital subscriber multiplex system. Refers to a system that operates as follows. Therefore, a gain-to-gain subscriber loop refers to a subscriber loop provided by a multiplexed transmission path. In a preferred embodiment of the invention, both the subscriber channel formed by the carrier and the voice frequency portion of the subscriber channel from the remote terminal to the subscriber are tested from standard test facilities. A single metal wire test pair is provided between the central office and the remote terminal of the gain system for testing the metal wires of the audio frequency drop-in lines for subscribers served by multiple carriers. . Additionally, a test control device is connected in tandem between the standard test facility and the central office switch, the control device connecting the metal wire pair at one end to the test facility and at the other end to the subscriber voice frequency drop-in line. It responds to the standard test start signal by doing so. At the same time, the subscriber channels formed by the carrier are reflectively or absorptive terminated, allowing automatic testing from the test control equipment through the central office switch. The test operator can thus carry out standard metal wire tests on the subscriber's audio frequency drop-in line, while the carrier-formed part of the subscriber loop is automatically tested from the test controller. . The test equipment is capable of completely testing the subscriber loop formed by each carrier, including both the carrier section and the metal line section. Additionally, the test is responsive to standard test signals, either manual or automatic. Finally, the testing of the parts formed by the carrier is controlled independently of the type of carrier system, and the actual tests performed are compensated for the particular type of service provided by the channels of the carrier system. . This embodiment will be described below with reference to the drawings. Referring to FIG. 1, a general block diagram of a gain versus gain test system according to the present invention is shown. The system in Figure 1 is located at central office location 10.
and a remote location 11. Central office location 10 includes a central office terminal 12 of a gain system. Terminal 12 connects outbound transmission facility 13 and inbound transmission facility 14 by using well-known analog or digital multiplexing techniques.
provides a subscriber channel created by the carrier via the carrier. In this way, the terminal 12
3 and 14, or time multiplexed digital channels on facilities 13 and 14. Corresponding remote terminals 15 of the gain system separate the signals on these multiplexed channels into a plurality of voice frequency analog signals on local drop lines for distribution to a plurality of subscriber telephones 17. Central office location 10 includes a central office switch 18 which may be any standard central office switching system, such as an electronic, crossbar or step-by-step switching system. Central office switch 1
8 connects the audio frequency vs. gain terminal on conductor 19 and a plurality of metal wire loop terminals (connected to subscriber telephone 21 via metal wire loop 20) to another loop, inter-office trunk 22 (telephone system (a central office trunk connected to another central office in a central office that carries outgoing voice frequency signals from a central office subscriber telephone to the other central office subscriber telephone)
Alternatively, it serves as an interconnect to the test trunk 23. Central office location 10 also includes a standard repair service receiving board (RSB) typically used to access wire loop 20 via test trunk 23 and central office switch 18 for testing purposes.
It includes a trunk 25 connected to 24. The RSB 24 typically includes either a manual local test console to manually test the loop 20 or automatic test equipment to automatically test the loop 20. The primary function of RSB 24 is to test loop 20 when it receives a report of a fault from a subscriber. Test trunk 25 from RSB 24 is connected to test trunk 23 through gain test controller 26. Generally, the pair gain test controller 26 is connected to a local loop connected to line 19 to the pair gain terminal via the pair gain system 12-15.
Allow RSB24 to test access. Access to the local service line 16 is provided through a central office test unit 27, a wire pair 28 and a remote terminal test unit 29. A single metal line pair 28 is sufficient to access multiple local service lines 16 served by the same pair of gain systems 12-15 (or shared by parallel systems). . In addition to providing wire access to the local service line 16 via the wire pair 28, the pair gain test controller 26 also connects the channels formed by the carriers of the pair gain systems 12-15 through the central office switch 18. has direct access to the central office terminal. The remote terminal test unit 29 provides preselected test terminations at the remote terminal ends of the channels formed by the carrier, thereby allowing round-trip testing of each of the channels formed by the carrier from the gain test controller 26. is allowed. The channel test performed by the pair gain controller 26 can be fully automated and can be performed simultaneously with the test of the local service line 16 from the RSB 24. It will be appreciated that the system of FIG. 1 has access to all parts of the counter-gain system for testing purposes. Local loop and individual access to subscriber terminals is provided through metal wire pairs 28. At the same time, test access is made to the channels of the gain system through test trunk 23 and central office switch 18. Because the test procedure involves providing normal signal conditions to the central office pair-gain channel terminals, the channel test portion of the system is completely independent of the type of pair-gain system involved. In this way, the same test equipment can be used for both analog and digital gain systems independent of the number of channels provided by the system. A test connection is established from the RSB 24 to the central office channel terminal by simply dialing the telephone number of the line to be tested. RSB 24 then performs a standard connection test to the central office terminal of the paired gain channels. Tests on the subscriber channel itself
After initiating access, the RSB 24 performs a standard test sequence and does not need to perform any special test procedures for the subscriber loop formed by the carrier. This feature relieves the RSB of an enormous administrative burden on the central office, which has a mix of wire subscriber loops and carrier loops. In order to better understand the automatic procedure for setting up a test connection to a subscriber loop formed by a carrier, consider the simplified circuit diagram of FIG. Equipment blocks in FIG. 2 that correspond to equipment units in FIG. 1 are designated by the same reference numerals for convenience. A dual gain system is a multiplexed digital system having a digital signal channel and a digital audio channel. These digital signal channels are used to exchange control information between the central office location 10 and remote locations 11 of the dual-gain test system. In frequency-divided analog-to-gain systems, the signal channels described above are provided by separate frequency bands. In the circuit diagram of FIG. 2, the RSB (not shown) passes through normally closed contacts 40 in the gain test controller 26 and accesses the test trunk 23 via the RSB trunk 25. In this way, the RSB trunk 25 is connected to the metal wire loop 20
(not shown in FIG. 2). The telephone number of the subscriber connected to the gain system is connected to the RSB trunk 25 and the central office switch 18.
, a connection is made via line 19 to a codec 69 in central office terminal 12 of the gain system.
To begin the test procedure, the RSB tester applies the test voltage (+116V) to the chip side of the test trunk. This is performed by operating the reverse station key (REV) and the normal station key (+STA) on the test console. +116V voltage is normally closed contact 4
0 to a test voltage detector 41 in terminal 12. In response to detecting the test voltage, codec 69 applies a tone on line 19 which is transmitted through switch 18 and trunk 23 to tone detector 42 in gain test controller 26. At the same time, the NSEIZE signal is
7 and the signal is used to determine whether the test circuit is already in use.
If it is already in use, a busy acquisition signal (SZEBSY) on lead 68 will notify the tester of the condition. At the same time, codec 69 transmits a test code in a signal bit stream on outgoing line 13. There is a method for providing signal functions for each channel in a standard D-type digital channel bank.
No. 057,333, filed July 13, 1979, by S.G. Brolin. The signals generated in codec 69 initiate a handshake routine that ensures that the appropriate test trunk is associated with the appropriate gain system and the appropriate subscriber channel within that system. When a tone is detected by tone detector 42, the output is applied to AND gate 43, which is partially enabled. This signal indicates a request for a test connection and specifies the particular test trunk to be connected. Note that tone detector 42 is provided for each test trunk. Upon receipt of the test code on outgoing line 13 by codec 44 in remote terminal 15 of the counter-gain system, an NSEIZE signal is transmitted on line 14. This NSEIZE signal acts as if it were a logic signal sent on phantom line 45, shown as a dotted line for illustrative purposes. Remote terminal test unit 29 utilizes the data link channel on incoming line 14 to transmit the SEIZE RC signal to central office test unit 27. One approach to forming additional data links in a standard D-type digital channel bank is disclosed in U.S. patent application Ser. No. 966,637 to G.E. ) is stated in In response to the SEIZE RC signal, central office test unit 27 sends a SEIZE signal to gain test controller 26 to complete enabling of AND gate 43. In response to the output of AND gate 43,
Gain test controller 26 selects a particular tester unit 59 and associated tester trunk for assignment to this test operation. In this way, the pair gain test controller 26 controls the first
includes a plurality of tester units that are scanned to determine the location of available non-busy tester units. The gain test controller 26 then runs a test sequence on the tester unit itself to check its general functionality and perform calibration. If the result of this test is unsuccessful, the busy flag for that tester unit is set, the next available tester unit is selected,
At the same time, the alarm inside the station is activated. Once a suitable tester unit 59 is selected,
The output of AND gate 43 produces a PROCEED signal on lead 47 to central office test unit 27. This PROCEED signal appears on different leads depending on the particular tester unit selected. In the central office test unit 27, this
The PROCEED signal generates a PROCEED CR signal which is transmitted via a signal channel on outgoing line 13 to remote terminal test unit 29. PROCEED
The CR signal is shown as a dotted line for illustration purposes.
It acts as if it were a logic signal sent on the virtual line from gate 46. At the same time, conductor 4
The PROCEED signal on 7 enables AND gate 48. In remote terminal test unit 29,
The PROCEED CR signal provides the NGATE signal on lead 48 to the remote terminal 15 of the pair gain system. This NGATE signal on lead 48 activates the channel test relay for the channel under test, thereby activating contacts 49 in terminal 15. Contact 49 disconnects local drop 16 from the gain channel provided by codec 44 and connects local drop 16 to line 50 to remote terminal test unit 29. Contact 49 also connects the subscriber channel terminal of codec 44 to battery monitor circuit 51 and test termination circuit 62 in remote terminal test unit 29. The PROCEED CR signal also activates the relay and
The normally open contact 52 is closed to connect the line 50 to the test pair 28. Battery monitor 51 examines the low noise voltage source (the transmit battery) used in the voice circuitry on the subscriber terminal of codec 44 and indicates that contacts 49 on the channel test relay are operating properly. Signal AND gate 5
3 to one input. AND gate 53 is
fully enabled by the PROCEED CR signal, which when enabled generates the PROCEED RC signal, which
channel back to the central office test unit 27. The PROCEED RC signal acts as if it were a logic signal sent on an imaginary line leading to AND gate 53 or AND gate 48, shown as a dotted line for illustration purposes. When the PROCEED RC signal is received at the central office test unit 27,
AND gate 48 is fully enabled, and gate 48 closes normally open contact 55 through OR gate 54, connecting test pair 28 to pair gain test controller 26 via line 56. The output of OR gate 54 is also on conductor 57.
A SLEEVE signal is generated which actuates contact 40 in pair gain test controller 26. In this way, the RSB test trunk 25
It is separated from the trunk 23. Test voltage (+
116V) is removed from the test trunk 25, the tester unit 59 is connected via the trunk 23, the central office switch 18 and the line 19 to the subscriber terminal on the codec 69 of the central office terminal 12 of the gain system. Ru. RSB trunk indicator 25 is connected through contact 55 to test pair 28 via contact 58 and line 56. Once these connections are complete, gain test controller 26 generates a LOCK signal on lead 60 to central office test unit 27. The signal on conductor 60 is connected to OR gate 54
was partially enabled by the output of
Enable AND gate 61. The PROCEED signal on lead 47 is removed at this time. AND
The output of gate 61 is ORed to keep contacts 55 and 58 closed during the test operation.
is applied to gate 54. When the LOCK signal on conductor 60 is removed, the relay contacts are restored and the PROCEED CR signal is terminated, restoring the remote connection. The system of FIG. 2 is currently in a state of running a test series. A manual or automatic test console connected to RSB trunk 25 is currently connected to local service line 16 through test pair 28 . This provides a direct metal wire connection and allows the tester or automated equipment to perform any regular test procedures used for metal wire loops on the local service line 16 and subscriber telephone 17. It becomes possible. These tests include, for example, leakage tests between conductors or between one conductor and the earth, tests for external voltages on the line, shock tests for ringers on the line, etc. A tester at the RSB may also monitor the local service line 16 by connecting a telephone set to the RSB line. Simultaneously with the metal wire access test as described above, the tester unit 59 is connected to the subscriber channel terminal on the codec 69 and the termination circuit 62 is connected to the subscriber channel terminal on the codec 69.
is connected to the subscriber side of the channel unit under test. Termination 62 provides a test termination for the subscriber channel, thus allowing tester 59 to test the subscriber channel under automatic control. These tests include AC transmission tests such as open channel loss, echo return loss, and empty channel noise measurements. These terminations are also off.
Futsuku, chip party identification area, banknote storage,
It is possible to detect various forms of return signals and single-party and multi-party ringing signals. Here, the chip-party discernment chi is as follows. There are two parties, a chip party and a ring party, connected to a single line consisting of a chip conductor and a ring conductor. Since only one line is used at a time, it is necessary to identify which subscriber is requesting service. To do this, the chip party phone has a connection to the earth. The ground connection is checked to automatically identify the party as a chip party for off-hook billing purposes. Note that the majority of the test circuitry is provided in the tester unit 59 of the central office gain test control circuit 26. The only circuit provided at remote location 11 is termination 6, which consists of simply reflective and absorptive terminations and a ground connection.
It is 2. Modification of these terminations is accomplished by using multi-party ringing or deposit or return signals as control codes to control these terminations. Since the subscriber channels are not connected to the subscriber drop line 16, these telephone control codes can be used as signal codes to control termination in the termination circuit 62. It will be appreciated that the device described above can test both the metal wire subscriber loop 16 and the subscriber channels formed by the corresponding carriers in lines 13 and 14 separately and simultaneously.
The metal wire drop test series is performed manually or automatically using the same circuitry used for conventional metal wire loops extending from the central office. This ensures that whether service is received from a central office by a wire loop or by a subscriber channel formed by a carrier,
RSB will be able to use standard testing procedures for all subscribers. This greatly reduces the administrative burden required to make the central office function. At the same time, tester unit 59 can perform automatic test sequences on subscriber channels formed by selectively terminated carriers in the gain-pair system. In this way, the entire link from the central office to the subscriber is tested simultaneously to check whether the subscriber line connection is fully available and operational. The results of the tests performed by the tester unit 59 are relayed to the RSB by applying test response tones and voltages to the RSB trunk 25, providing an audible or visual signal to the tester and indicating that the automated channel test is successful. Indicates that it has been completed. Execution of the entire interconnect sequence can be performed in about 1 second.
All steps in the interconnection procedure are automatically timed and a redirect signal (fast busy signal) is sent back to the RSB if a timeout occurs or an incorrect signal is received. A new attempt is then initiated to establish a test connection. test·
The final opening of trunk contact 58 is determined by the RSB test.
There is a delay until the +116V test signal is removed from the trunk 25 chip conductor. This informs the tester that the test connection has been properly set up. The overall operation of the gain versus gain test system shown in FIG. 1 has been outlined above in conjunction with FIG. 2. The remaining figures show the detailed circuitry necessary to perform the operations described above. FIG. 3 shows a detailed block diagram of one of the central office channel units in the codec 69 of the central office terminal 12 of the dual gain system. The central office channel unit has a hybrid transformer 70;
Connected to the transformer 70 are a chip conductor 71 and a ring conductor 72 of a particular subscriber's central office terminal. A ringing detector 73 is connected to ring conductor 72 through one winding of hybrid transformer 70 and is connected to conductors 71 and 72 by the central station.
It serves to detect the ringing signal applied to the Detection of ringing signals provides input to control circuit 74 which encodes these ringing signals via modulator 75 and transmits them via line 76 to outgoing transmission facility 13 (FIG. 1). do. Chip conductor 71 is connected through the other winding of hybrid 70 to test voltage detector 41, the output of which is also connected to control circuit 74. As mentioned in connection with Figure 2,
Test voltage detector 41 is connected to + on chip conductor 71.
Designed to detect 116V test signals. A test voltage, such as +116 volts appearing on chip lead 71, is applied to control circuit 74, and in response, control circuit 74
Generates NSEIZE signal. The NSEIZE signal is sent from the central office codec 69 to the central office test unit 27.
control. This is codec 4 in Figure 2.
Provides similar control to that described above with respect to 4. At the same time, a tone is applied onto conductors 71 and 72, which is detected by detector 42 (FIG. 2). The audio signals appearing on conductors 71 and 72 are transmitted through hybrid 70 and low pass filter 78 to modulator 75. These audio signals are encoded by modulator 75 and sent out on line 76 towards outgoing transmission facility 13 . The incoming signal from transmission facility 14 is demultiplexed and provided via lead 7 to demodulator 80 which demodulates the audio frequency signal and passes it through a low pass filter 81 and hybrid transformer 70 to lead 71. and 72. The encoded off-hook signal appearing on conductor 79 is demodulated by demodulator 80 and provided to control circuit 74 to activate relay 82. Relay 82 then closes normally open contact 83 and relays the off-hook condition to the central office by closing the signal path between conductors 71 and 72. FIG. 4 shows the ringing signal detector 73 of FIG.
A detailed circuit diagram is shown. Input conductor 100
The ringing signal applied to the circuit is supplied through a blocking capacitor 101 to a noise filter consisting of a resistor 102 and a capacitor 103.
Capacitor 101 blocks direct current. The positive and negative half waves of the ringing signal are connected to resistors 105 and 10
6, respectively. Current bias resistance 1
04 and 107 are connected to a positive voltage source 108 and a negative voltage source 109, respectively. resistance 104
The midpoint of resistors 106 and 107 is connected to the base of transistor 110, and the midpoint of resistors 106 and 107 is connected to the base of transistor 111. Capacitor 103 is connected to resistors 105 and 10
It is connected to the midpoint of 6. When the current drawn through resistor 105 increases to a high enough level to exceed the bias current through resistor 104, transistor 110 turns off. When the current flowing through resistor 106 exceeds the bias current flowing through resistor 107, transistor 111 becomes conductive. Diodes 114 and 115 serve to protect against reverse voltage between the bases and emitters of transistors 110 and 111, respectively. The collector of transistor 110 is connected to the base of transistor 116 and bias resistor 112. When transistor 110 is off, transistor 116 is on and this common node is grounded. Thus, a large positive or negative input signal will cause transistor 111 or transistor 116 to conduct, grounding the common node of their collectors. By grounding this common node, resistance 1
A current flows through 20, discharging capacitor 119 connected to power supply 108, thereby charging it to the supply voltage level. When the voltage on capacitor 119 becomes low enough, an output signal appears on conductor 121. Resistors 118 and 120 connected in series across capacitor 119 control the recovery time of the output circuit. Note that the ringing signal detector of FIG. 4 is responsive to both single party and multiparty superimposed ringing signals. Conductor 1
The signals on 21 are applied to control circuit 74 of FIG. 3, which relays these ringing signals via modulator 75 and line 76 to the remote terminal. FIG. 5 shows a more detailed block diagram of the gain test control circuit 26 of FIGS. 1 and 2. The test control circuit in FIG. 5 includes a control circuit 130,
It consists of a tester unit 131, a tone detector 42, a maintenance display device 132 and various logic circuits. RSB trunk tip, ring and sleeve conductors 25 are fed through K2 contact 58 to test pair 56 or through K3 contact 144 to test trunk 23 to the central office switch. The normally closed contact 40 of the K2 contact 58 is the same as that shown in FIG. Trunk 23 is
It is connected to the tone detector 42 through the K3 contact 133. Therefore line 23 from the central office switch
The appearance of the upper tone is detected by tone detector 42 and partially enables AND gate 134. AND gate 134 is fully enabled by the SELECT signal on lead 135 from control circuit 130. The detailed logic circuit in Figure 5 is
Conductor 135 is repeated for RSB test trunk 25 and each tester unit.
The SELECT signal above selects the specific tester
unit 131 and the tone detector output helps select the particular test trunk to be used. The output of AND gate 134 is connected to control circuit 130 and simultaneously to flip-flop 136.
supplied to the input. flip flop 136
ONE output is added to relay drive circuit 137 and K2
Activate relay 138. Relay 138 is K2
Contact 58 is actuated to disconnect the subscriber connection, connect trunk 25 to test pair 56, and connect tester unit 131 to trunk 23. Since each test trunk has its own tone detector, simultaneous detection of adjacent tones can occur with multiple test trunks. To eliminate the possibility of a tester unit being connected to more than one test trunk, the output of all tone detectors is connected to the D of each flip-flop 141.
The output of a given tone detector is applied to the edge of its associated flip-flop 141.
Added to the triggered clock input. Note that since delay delay element 700 does not cause a change in the D input until after the clock edge, a given tone detector cannot operate its associated flip-flop 141. This feature limits the possibility of ambiguous tone detection during the time window determined by delay element 700 (50 nanoseconds or less in this example). When activated, flip-flop 141 provides a signal to relay driver 142, which in turn provides a signal to relay driver 142,
Activate. K3 contact 144 connects trunk 25 to ground through resistor 145 and K3 contact 146. The output of flip-flop 141 is also
AND gate 147 is partially enabled.
AND gate 147 is 120 IPM on conductor 148
(120 interruptions/minute) signal fully enabled. By attempting to access the busy central office test trunk 23 in this manner,
K3 contact 144 connects RSB trunk 25 to intermittent ground and provides a fast busy signal indicating to RSB 24 that it should retry access.
Furthermore, when SZEBSY is received, the conductor 701
Or, if a problem occurs in the interconnect series and the tester unit to be assigned is not available,
A means is provided for control circuit 130 to operate flip-flop 141 via its preset input. Sleeve conductor 140 is connected to current detector 702
provides a means for separating the fast busy indication from the test trunk in conjunction with the test trunk. The test sequence performed by tester unit 131 is performed by test selection conductor 151 under control of control circuit 130. The results of the test are sent back to control circuit 130 by lead 159. Display unit 132 is used to identify appropriate fault correction procedures. Control circuit 130 also sends a PROCEED signal on lead 47 and on lead 6.
0 and generates a LOCK signal on the conductor 51.
Receive SLEEVE signal. These conductors 47, 6
0,51 are all connected to the central office test unit 27. K3 contact 133 locks tone detector 42 out of circuit when a fast busy indication is being sent back to RSB trunk 25. Flip-flop 136 also connects ZERO output lead 1
A busy signal on 52 is provided to control circuit 130.
The output of AND gate 134 on conductor 153 indicates which tester unit is assigned to control circuit 1.
30. A detailed circuit diagram of a tester unit, such as tester unit 131 of FIG. 5, is shown in FIG. The tester unit of FIG. 6 is under the control of nine test relays K5-K13 (not shown in FIG. 6) operated by nine signals on conductor 151 of FIG. In FIG. 6, the chip conductor 16
0 and ring conductor 161 are test trunk 2
3 through various relay contacts
It is connected to coil 162. Test signal source 1
63 is connected to one winding of hybrid coil 162 through resistor 164 and amplifier 165. The test signal thus generated by signal source 163 is transmitted through hybrid 162 to chip conductor 160 and ring conductor 161 of test trunk 23. AC tests such as return loss and noise are performed using the signal from signal source 163. The frequency of this test signal is swept over a portion of the audio frequency range to reduce the effects of interhybrid reflections.
K10 contact 166 inhibits these AC tests by grounding the input to amplifier 165. The return signal from test trunk 23 passes through hybrid coil 162 to filter 16.
7 and the output of the filter is applied to a variable gain amplifier 168. K11 contact 169 changes the gain of amplifier 168, allowing increased sensitivity when measuring noise signals. The output of amplifier 168 is applied to rectifier 170 and the output of the rectifier is applied to comparison circuit 171. Comparison circuit 171 compares the output of rectifier 170 to various threshold values and provides output signals on conductors 172 and 173 when these thresholds are crossed. One threshold is used, for example, for round loss and return loss, and another threshold is used to measure noise. K3 contact 175 inverts the normal transmit battery voltage on ring conductor 161, and K5 contact 176 inverts the polarity of the superimposed ringing signal. K3 contact 177 reverses the polarity of the coin voltage applied to chip conductor 160. K6 contact 178 applies a ringing signal to ring conductor 161 while simultaneously grounding tip conductor 160 through K6 contact 179. K8 contact 180, which is normally closed, has a resistance of 18
1 and the coil of the hybrid transformer 162 to provide earth air to the chip conductor 160. K8 contacts 182 and 183 reverse the tip and ring connections, thereby placing battery or ringing on tip conductor 16 instead of ring conductor 161.
Supply to 0. K13 contact 187 is chip conductor 16
0 and the ring conductor 161, and at the same time open the chip conductor connection. K7 contact 192 connects the coin voltage to chip conductor 160 through resistor 193, and K7 contact 194 connects the coin voltage to chip conductor 160 through resistor 193.
When the K13 contact 187 is activated, it removes the terminating resistor 188 from both ends of the chip and ring conductors.
K12 contacts 195 and 196 are hybrid 16
2 to conductors 197 and 198, and
While forming the signal path between the unit and the central office switch, trunk 23 is connected through K12 contacts 197 and 184 to conductors 198 and 186, thereby forming a metal wire test pair. Voltage detector 200 is normally connected to chip lead 160 through K12 contact 197 to monitor the chip voltage and provide an output signal on lead 201. Current detector 202 is connected in series with the transmit voltage provided through K5 contact 175 to detect the off-hook loop current and the coin or ANI
Provides an indication of this line current on conductor 203 for both chip current. K9 contact 205 provides an off-hook signal on conductor 206 that is transmitted via the data link to the remote terminal to return the remote end of the subscriber channel formed by the carrier to an on-hook condition. This allows the ringing signal to be used to control the remote end of the channel. The tester unit of FIG. 6 selectively provides AC audio frequency test signals, DC and ringing/coin signal conditions to test trunk 23 under the control of nine test relays. At the same time, the tester unit provides an indication of line voltage (on lead 201) and line current (on lead 203) and leads 172 and 173 for the results of the AC test.
Provide instructions on. The test unit controlling the tester unit in Figure 6
The relay is connected to the conductor 15 from the control circuit 130 in FIG.
1 is under the control of the signal above. Control circuit 130 consists of a logic circuit that provides all necessary control signals or a microprocessor that provides the same functionality. A block diagram of a microprocessor suitable for use as control circuit 130 of FIG. 5 is shown in FIG. The microprocessor of FIG. 7 may be, for example, a Mostek MK3870 single chip microcomputer. The microprocessor of FIG. 7 includes a read only memory 210 in which is stored a control program for controlling the remainder of the unit. Memory 210 is accessed by an address code in address register 211 (which address code is retrieved from adder circuit 212). One input to summing circuit 212 is taken from bus 213 and is connected to all of the major units of the microprocessor of FIG.
The other input to circuit 212 is address register 21.
1, whereby the address in address register 211 is incremented or otherwise arithmetic modified to produce the appropriate sequence of program code word locations in memory 210. Multiple scratch pad registers 214
is also provided for storing intermediate results of calculations. Scratch pad register 214 is accessed by scratch pad address register 215 loaded from bus 213. Arithmetic and logic unit 216, whose inputs and its outputs are connected to the bus, is used for all arithmetic and logic operations performed by the microprocessor. A second input of arithmetic and logic unit 216 is provided by an accumulator register 217 connected to bus 213. Program instructions accessed from read-only memory 210 are applied by bus 213 to instruction register 218, whose output directs the operation of all other circuitry in the microprocessor. It is added to control logic 219 for control. A plurality of ports 220, 221, 222 and 223 are connected to bus 213 and provide independent outputs on conductors 224, 225, 226 and 227, respectively. Port 222 also provides a STROBE signal on conductor 228 when new data is loaded into port 222 and ready for output. Further details of the MK3870 microprocessor, as well as the instruction set used in this microprocessor, can be found in "Mostek F8 Microprocessor Device", July 1977, available from Mostek Corporation. It is being Various ports of the microprocessor of FIG. 7 are used to send and receive various control signals shown in FIG. Port 220 typically connects conductor 135 (sixth
Figure) provides SELECT output as well as busy and alarm signals. Since port 220 is reserved for these output signals, these output signals can be provided at any time during the test sequence or continuously. Port 221 provides and is always available for receiving the SLEEVE signal on lead 51 as well as the busy signal on lead 152. Port 223 provides tester address and clock signals to control various inputs and outputs to port 222. Port 222 provides a bidirectional data bus that is connected to conductors 153 under control of read/write and address signals from port 223.
(Figure 5) Upper tone detector output and lead 15
9 receives the test result signal on conductor 47.
PROCEED signal, LOCK signal on conductor 60,
A test control signal is generated on conductor 151 and a display signal is generated on display 132. A list of the various signals on the ports of the microprocessor of FIG. 7 is shown in the following table.

【table】

【table】

【table】

【table】

【table】

【table】

【table】

8 shows a detailed logic diagram of the central office channel test unit shown as block 27 in FIG. The test unit of FIG. 8 includes a test pair 56 from the gain test controller 26 of FIG. 1, which extends via test pair 28 to a remote location. The test pair is interrupted by a normally open K16 contact 250, which serves to form a connection to the test pair from the pair gain test controller to the remote location through the channel test unit. Additionally, a test alarm signal on lead 251 taken from the microprocessor of FIG. 8 is applied to a data transmitter, discussed below in connection with FIG. This test alarm signal is sent to the remote terminal to indicate that a certain test sequence has failed or timed out, and to allow the test connection to be terminated at the remote terminal when such a failure occurs. Ru. As previously noted, the tester unit of FIG. 6 is capable of generating an on-hook signal during the execution of a test sequence. This on-hook signal appearing on conductor 206 is passed through inverter 710.
is supplied to the NOR gate 253, and the NOR gate 2
The output of 53 appears on lead 254 and is applied to the data transmitter of FIG. on the conductor 47
The PROCEED signal is also connected to the gain test controller 26,
Strictly speaking, it is generated by the microprocessor shown in FIG. As shown in the table, this signal is generated when the tester unit is selected and pretested for operational status. The signal on conductor 47 is applied to NOR gate 255 through inverter 711;
The output of gate 255 is connected to OR gate 256 and
Added to AND gate 257. The output of OR gate 256 on conductor 258 is shown in FIG.
A PROCEED CR signal is formed and also applied to the data transmitter of FIG. NOR gate 255
The remaining input of is connected to positive voltage source 2 through resistor 260.
59. By K13 contact 261 (K13 relay 291 generates SEIZE signal),
This input to NOR gate 255 goes high, thereby inhibiting the generation of the PROCEED CR signal until the SEIZE signal is sent to pair gain test controller 26. The LOCK signal on lead 60 is also generated by the microprocessor of FIG. (See table) Once a test is selected and all handshake procedures are completed, execution of the test sequence begins.
The LOCK signal on conductor 60 is then applied to AND gate 262. The output of AND gate 257 and the output of AND gate 262 are NOR gate 2
The output of the NOR gate 263 is inverted by an inverter 264 and applied to a relay drive circuit 265. The output of the drive circuit 265 is
Activating K16 relay 266 , which closes K16 contact 267 , thereby providing ground air on SLV conductor 57 . As discussed in connection with FIG. 2, this signal on conductor 57 is used to activate relay contact 58 in pair gain test control 26 to complete the test connection. This logic circuit activates K16 relay 266 with the PROCEED signal on lead 47 and the PROCEED RC signal on lead 268. Once K16 relay 266 is activated, the LOCK signal on conductor 60 holds relay 266 activated when the PROCEED signal on conductor 47 terminates. AND gate 257 is AND gate 48 in FIG.
It will be appreciated that AND gate 262 corresponds to AND gate 61 of FIG. AND
One of the remaining inputs to gate 257 is the fifteenth
from the data receiver described below in connection with the figure.
PROCEED Taken from RC conductor 268.
The final input to AND gate 257 is taken from the output of NOR gate 269, whose inputs are connected to TESTALM RC conductor 270 and SEIZE RC conductor 271 (both of which are connected to the first
5 (coming from the data receiver in Figure 5). When the SEIZE RC signal on conductor 271 disappears or an alarm (TESTALM RC) occurs at the remote terminal, all relays in FIG. 8 are restored by this logic. Therefore, if a PROCEED RC signal has already been received on lead 268 and a SEIZE RC signal has not already been received on lead 271, then
It will be appreciated that the SLV signal on conductor 57 is not generated. It is also required that no TESTALM RC signal is received on conductor 270, indicating an alarm signal at the remote terminal. The remaining inputs of AND gate 262 are the output of inverter circuit 264 indicating that the SLV signal has been generated on lead 57 and the SEIZE RC signal is received on lead 271 and the TESTALM RC signal is still being received on lead 270. The output of NOR gate 269 indicates that the The inverted output of NOR gate 263 is connected to NOR gate 253 and
Forms the second input to NOR gate 256. The purpose of this circuit is to send a specific on-hook signal (which may be multiplexed) to a remote terminal.
The purpose is to fix the At this time, NOR gate 2
The output of 63 is capable of generating the PROCEED CR signal on lead 258 and the output of
The PROCEED signal is ready to terminate. The PROCEED RC signal on conductor 268 is inverted by inverter 272 and sent to flip-flop 273.
is added to the D input of The clock signal is passed from the inverted output of NOR gate 255 to flip-flop 2.
73. On the falling edge of the PROCEED signal on lead 47, flip-flop 273 produces an output on lead 274, which is applied to NOR gate 275. That is, flip-flop 273 serves to remember that the PROCEED RC signal was received on conductor 268 at the appropriate point in the sequence, and this stored information is used later. Flip-flop 273 is reset when the SEIZE RC signal is removed from conductor 271. This allows termination of the SEIZE signal to the central office terminal. The NSEIZE signal is received on conductor 77 as discussed in connection with FIG. The signal on conductor 77 is
is added to the AND gate 277, and the AND gate 2
Another input to 77 is the MJO signal on lead 278. This MJO signal indicates that a main alarm condition has been received from the carrier system. The output of AND gate 277 is applied to a relay drive circuit 279 which actuates K15 relay 280. When the relay is actuated, the K15 relay 280 closes the K15 contact 281, causing a drop on the conductor 282.
Provides TMAJ signal. This alarm signal is used to signal the main alarm device in the carrier system under test and is used to terminate the test sequence and apply a slow busy signal to the RSB. The NSEIZE signal on conductor 77 and the output of flip-flop 273 are combined in NOR gate 275 whose output is applied to NOR gate 283. The remaining input to NOR gate 283 is taken from the signal on lead 271. The output of NOR gate 283 is applied as a clock to flip-flop 295.
It acts as a logic signal that activates K13 relay 291 or K14 relay 287 depending on the signal at the D input of flip-flop 295. When a signal (which indicates that the metal wire pair is already in use for another test) appears on conductor 294, K14 relay 287 operates, causing a signal to appear on conductor 281.
Generates a SZEBSY (busy seize) signal. As noted in connection with Figure 2, this SZEBSY signal is used to indicate that the facility is busy. If the INHIB signal is not present on conductor 294, K13 relay 291 operates and transfers the SEIZE signal (conductor 273) to gain test controller 26 (second
Figure). K16 contact 296 activates INHIB conductor 294 if a test is in progress. (on conductor 47 from gain test control device 26)
When the PROCEED signal is removed, flip-flop 273 is clocked through NOR gates 275 and 283, and K13 relay 291 is restored. FIG. 9 shows a remote channel such as that found in the codec 44 of the remote terminal 15 of the counter-gain system.
A block diagram of the unit is shown. Input line 300 from the demultiplexer is applied to a demultiplexer circuit 301 where the digital signal is converted to an audio frequency signal and applied to a hybrid transformer 302. Control signals from the digital pulse train are applied to control circuit 303. In this manner, a control signal indicating, for example, that ringing is to be applied to the local telephone drop-in line, is used to activate K7 relay 304. The NGATE signal discussed in connection with FIG. 2 appears on conductor 48 and is applied to control circuit 303. This signal is
Activate K18 relay 305 and set up the test connection. The audio signal transmitted through hybrid transformer 302 is transmitted through chip conductor 306 and ring conductor 3.
Appears on 07. (These conductors are connected to the subscriber telephone circuit by local drop wires.) Audio frequency signals received from the subscriber telephone by conductors 306 and 307 are transferred to the hybrid transformer 3.
02 to the modulation circuit 308. In modulation circuit 308, these audio frequency signals are converted to pulse amplitude modulated signals on conductor 309, which pulse amplitude modulated signals are applied to a coder/multiplexer circuit for transmission on incoming transmission line 14 of FIG. When a subscriber goes on-hook, the loop current flowing through the telephone is detected by current detector 310 and provides an off-hook signal on lead 311 to control circuit 303. This off-hook signal is transmitted via lead 312 to modulator 308 which encodes the off-hook signal and transmits it as a stream of digital pulses on lead 309. This off-hook signal is used at the central office terminal as a service request during normal use of the telephone. The normal transmitter battery is connected to the resistor 3 from the negative voltage source 313.
14, a portion of one winding of hybrid transformer 302 and a ring conductor 307 to the subscriber telephone. A return path for this transmit current is provided by a circuit through chip conductor 306, a portion of the other winding of hybrid transformer 302, and resistor 315 to ground. K17 contact 316 disconnects the regular transmitter battery and connects ring conductor 307 to ringing signal generator 317. K17 contact 3
16 is operated by a K17 relay 304 which operates in response to the presence of a ringing code in the pulse train on conductor 300 as described above. K17 relay 304 also has K17 contact 330
provides a return path for the ringing signal through resistor 331. The K18 relay 305, which operates in response to the signal on conductor 48 (and the presence of a test code on that channel), is a K18
Activate contacts 318 and 319. K18 disconnection relay 305 until the test series ends
Locked by NGATE signal. As can be seen in FIG. 9, contacts 318 and 319 serve to connect local service lines 306 and 307 to test pair 50 of FIG. At the same time, these contacts connect hybrid transformer 302 to remote terminal channel test unit 29. In this way, the audio frequency wire circuit is extended from the central office to the local service line, while the channel itself is terminated at the channel test unit 29. FIG. 10 is a general block diagram of a remote terminal channel test unit shown as block 29 in FIGS. 1 and 2. Channel in Figure 10
The test unit consists of a pair of conductors 32 emanating from the remote channel unit of FIG.
5 and 326. Conductors 325 and 326 are contacts 327 of the K19 relay, which is normally closed.
and 328 to the termination circuit 62. As previously noted, during testing of each channel, the remote end of the channel unit is selectively terminated with passive termination elements to aid in the test sequence. Furthermore, these passive terminations are under the control of signals normally used to control multiparty linking or monetary signals when the subscriber loop is not under test. In this manner, the ringing signal detector 329 detects the generated conductor 32 to the remote end in response to control signals transmitted from the central station.
5 and 326 to detect the presence of a ringing signal or a coin control signal. K19 relay 331 (as described in connection with Figure 11)
When activated by the on-hook signal, detector 3
The output of 29 is applied to ringing signal logic circuit 330. The circuit 330 uses these ringing signals to control the operation of relays 331, 332 and 333. Conductors 325 and 326 are connected through the normally closed portions of K19 contacts 327 and 328 to a termination circuit 62 shown in general block diagram form in FIG. Line feed detection circuit 51 is connected to conductors 325 and 326 to detect the presence of a transmit battery supplied from the remote channel unit of FIG. Termination circuit 62 is under the control of relays 331, 332 and 333.
In detail, K20 contact 334 is K20 relay 3
32 and, when activated, provides a short reflective termination for conductors 325 and 326. If no such short termination exists, resistor 335
and 336 provide matched dissipative terminations for conductors 325 and 326. Resistor 335 and 3
The common junction between 36 is K20 of K20 relay 332
It is connected to diodes 337 and 338 through switching contact 340. On the other hand, these diodes are connected to the resistor 339 and the normally closed K21 contact 34.
It is grounded through 1. In this way, balanced ground air of either polarity is provided by K20 contacts 340 operated by K20 relay 332.
K21 relay 333 opens normally closed contact 341 to terminate the balanced connection. This connection is used to simulate automatic number identification or currency identification in remote subscriber telephones. Note that the only equipment needed at the remote terminal to perform a complete test of the subscriber loop in a gain-to-gain system is the set of artificial terminations 62 and the control circuitry necessary to select these terminations. All the complex equipment that generates the signals and evaluates the responses is located at a central station. Furthermore, the central office circuitry does not have to be duplicated for various different subscriber channels or gain systems, and thus can be used commonly to test a large number of subscriber channels. Also shown in FIG. 10 is a control circuit 3 used to control other parts of the channel test unit.
50 is shown. In detail, the conductor 45
The above NSEIZE signal is applied to control circuit 350,
The circuit 350 provides the NGATE signal on lead 48. The output of line feed detection circuit 51 is also applied to control circuit 350 along with various alarm signals and other test signals on conductor 351. Control circuit 350 also operates K22 relay 352 to
Close the K22 contact 715 and connect the metal wire pair 28 in a straight line 50
(Fig. 2). Data encoder 353 and data decoder 354 are also shown in FIG. These circuits receive signals from and transmit signals to control circuit 350. Data encoder 353 provides a serial digital signal on data conductor 355 for transmission to the central office via a data link. The central office serial data signal on conductor 356 is decoded by decoder 354 and sent to control circuit 35.
Added to 0. Encoder 353 and decoder 354 are discussed in detail in connection with FIGS. 14 and 15, respectively. FIG. 11 shows a detailed logic circuit of the ringgit signal logic circuit 330 of FIG. 10. 1st
The logic circuit in Figure 1 has four input conductors 400, 40.
1,402 and 403. The signals on these conductors are positive superimposed ringing and coin voltage on the tip conductor (conductor 400), negative superimposed ringing and coin voltage on the chip conductor (conductor 401), and positive superimposed ringing and coin voltage on the ring conductor. Detectors for negative superimposed ringing and coin voltage on the ring conductor (conductor 402) and negative superimposed ringing and coin voltage on the ring conductor (conductor 403). The signal on conductor 400 is applied to NAND gate 404, and the output of NAND gate 404 is applied to NOR gate 4.
05 to the set input lead of off-hook flip-flop 406. The ZERO output of flip-flop 406 is applied through relay driver 407 to activate K19 relay 331. The output of NOR gate 405 is also
The other input of NAND gate 408 is connected to on-hook conductor 409. The output of gate 408 is used to reset flip-flop 406, thereby activating relay driver 407 and K19 relay 331. K19 relay 331 connects tip conductor 325 and ring conductor 326 to ringing detector 329 (FIG. 10). When ringing is detected, logic circuit 330 restores K19 relay 331, thereby causing conductor 325 to
and 326 to terminal 62. Conductor 409
The new on-hook command above activates K19 relay 331, which again connects conductors 325 and 32.
6 to the ringing detector 330. The signal on conductor 401 is connected to flip-flop 41
1 set input. The Q output of flip-flop 411 is passed through relay driver 412.
Added to activate K20 relay 332. The signal on conductor 402 is connected to flip-flop 41
The Q output of flip-flop 414 is applied to the set input of flip-flop 414 through relay driver 415.
Added to activate K21 relay 333.
Flip-flops 411 and 414 are NOR
Responsive to the output from gate 416, the respective relays are reset and therefore restored. One input to NOR gate 416 is the on-hook signal on conductor 409. The other input is the inverted PROCEED CR signal on lead 417. Conductor 417 also serves as the remaining input to NOR gate 405. This ensures that all relays are in the restored state to be ready for a new ringing signal at the beginning of each new test. The signal on conductor 403 is connected to flip-flop 41
The Q output of flip-flop 418 is added as the other input to the set terminals of flip-flops 411 and 414. Flip-flop 418 is reset by the output of NOR gate 416. The outputs of flip-flops 411 and 414 are
It is added as the remaining input of NAND gate 404. A signal on conductor 400 or a reset of flip-flop 411 or 414 causes gate 40 to close.
An output of 4 is produced which is applied via NOR gate 405 to set flip-flop 406. In this way, K20 relay 33
2 is -T (conductor 401) or -R (conductor 403)
Acting on the ringing signal, K21 relay 333 -
Acts on R (conductor 407) or +R (conductor 402) ringing signals. Both relays 332 and 333 are restored by an on-hook command on lead 409. The operation of these relays is designed to handle specific test sequences initiated at the central office terminal described below. FIG. 12 shows a detailed circuit diagram of the line feed detection circuit 51 of FIG. This circuit consists of a chip conductor 325 and a ring conductor 326 (first
A pair of resistors 4 connected in series between
20 and 421. A pair of light emitting diodes 422 and 423 are connected to both ends of resistor 420 with opposite polarities. In this way, no matter which polarity of signal is applied across conductors 325 and 326, diode 422 or 423
Current flows through either one of the two. When such current flows through one of these diodes, the diode emits visible light, which is detected by light detection transistor 424 and connected to conductor 4.
provides an output signal on 25. As noted in connection with FIG. 10, the signal on conductor 425 is
5 and 326 are added to control circuit 350 to indicate that a transmit battery is present on 5 and 326.
This signal is used to confirm the completion of the cutting procedure described in connection with Figure 2, and is therefore used to ensure that the test sequence will not continue if this initial cutting operation is not successfully completed. be done. 12th
The current detector in the figure is also used to detect a fixed relay in the disconnected state and provide an alarm signal. FIG. 13 shows a detailed logic diagram of control circuit 350 of FIG. 10. Generally, these control circuits act as an interface between the data encoder 353, data decoder 354, and the rest of the circuit. In this way, the conductor 45
The above NSEIZE signal is applied to a NOR gate 450 whose output appears on lead 451 as a SEIZE RC signal that is sent back to the central office location to indicate that the appropriate channel has been identified at the remote terminal. . A TESTALM CR signal on lead 52 from the central office location indicates that an alarm condition has been reached during the course of a handshake sequence. This signal is OR gate 45
3, and the output of the gate 453 is connected to an inverter 462, a resistor 454, and a light emitting diode 4.
55 to a positive voltage source 456. Thus, when an alarm condition occurs at the central station, this signal illuminates an indicator lamp on the remote terminal to announce the alarm condition. At the same time, the test sequence ends and a fast busy signal is sent back to the RSB. PROCEED CR signal on conductor 457 is NAND
gate 464 and the NAND gate 46
The output of 4 is the NGATE on conductor 48 shown in Figure 10.
Consists of signals. The other input to NAND gate 464 is the signal on conductor 719,
This inhibits the NGATE signal while in the alarm state. OR gates 463, 465 and 458 and NAND gate 459 are local supplementary alarm (LMN)
Form a logic circuit. The gate 458 is connected to the conductor 45
When the PROCEED CR signal on 7 is low level and K22 relay 352 is activated, the auxiliary alarm signal is sent to lead 4.
Add on top of 60. The gate 465 is located on the conductor 48.
NGATE signal is high (inactive) and conductor 425
If a line feed current is detected above, an alarm is applied on conductor 460. Gate 463 indicates that an alarm condition exists and that
A low level (inactive) of the NSEIZE signal applies a low level on conductor 460. When any of the three OR gate outputs 463, 465 and 458 is at a low level, the output of the NAND gate 459 becomes active. This LMN local auxiliary alarm signal is also applied as a remaining input to OR gate 453 to illuminate alarm lamp 455. 12th
The output of line feed detection circuit 51, shown in detail in the figure, appears on conductor 425. This signal is OR
It is applied through gate 460 to output lead 461 . (This signal forms the PROCEED RC signal to be sent back to the central office location.) The output of NAND gate 464 is on lead 48.
The NGATE signal is formed, inverted by inverter 466 and applied to the remaining inputs of OR gate 465. The output of inverter 466 is also applied through relay driver 467 to operate K22 relay 352. When K22 relay 352 is activated, K22 contact 468 removes one input from OR gate 458 and one input from OR gate 460, thereby acting as a monitor for stack K22 relay 352 when no test is in progress. do. FIG. 14 shows a detailed block diagram of the data transmitter, ie encoder 353, shown in FIG. The data transmitter as shown in FIG.
It will be appreciated that each terminal in the illustrated system communicates via data links with data receivers such as those shown in FIG. 15 at other terminals. It is this data transmitter and data receiver that are used to exchange handshake signals that enable the establishment of a test connection as described above in connection with FIG. Referring to FIG. 14, three input signal states are indicated by the signals on conductors 500, 501 and 502. These signal states are set in the three bit positions of register 503 by the strobe signal on conductor 504. The contents of register 503 are applied to parallel to serial converter 505. converter 5
05 converts these parallel bits into a serial bit stream on conductor 506, which is applied to the multiplexer circuit of the gain system for transmission to the other terminal. The clock signal on conductor 507 is connected to counter circuit 50 which controls parallel-to-serial exchanger 505.
Added to 8. The frame signal on conductor 504 not only strobes new input data into register 503, but also clears counter 508 for generating the next serial bit stream, and the counter continues to the appropriate time slot in the DC bit stream. 5
Disable 08. FIG. 15 shows a data receiver for receiving data generated by the transmitter of FIG. In this manner, serial data arriving on lead 510 is applied into shift register 511 under control of the clock signal on lead 512. These clock signals are gated on conductor 5 by an AND gate 514 by the frame signal on conductor 515.
is generated from the clock current on 13. Note that shift register 511 has four bit storage locations. Due to the presence of the extra storage locations, the serial pulses received on conductor 510 are stored until they are received twice in succession and compared, and the retransmitted one is found to be the same as the original. It is possible to leave In this way, the final stage of shift register 511 is applied to comparator circuit 516 along with the output of the first stage of shift register 511. If these signals are the same, the output signal partially enables AND gate 517. On the other hand, AND gate 517
The output of is applied to the preset input of flip-flop 518. The remaining input to AND gate 517 is the clock pulse stream taken from the output of AND gate 514. In this way, flip-flop 5
Eighteen preset inputs are activated each time the signals from the first and second transmissions are the same. The O output of flip-flop 518 is applied to the D input of flip-flop 519. One output of flip-flop 519 is connected to register 502.
The contents of the last three bit positions of shift register 511 are gated and added to register 520. Flip-flop 518 is clocked by the frame signal on conductor 515, and flip-flop 519 is clocked by the output of AND gate 514. The flip-flop 519 is connected to the conductor 51
Cleared by the complaint signal on 5. As long as the output of comparator circuit 516 indicates that the signals at corresponding successive bit positions are the same, flip-flop 518 controls AND gate 5.
It will be appreciated that the preset state is held by the output of 17. flip flop 518
The Q output of is held at a high level since the D input is grounded. In this state, the frame signal on conductor 515 transfers the contents of register 511 to register 5.
Strobe and add in 20 minutes. Comparison circuit 516
indicates a mismatch, the flip-flop 51
8 is preset and flip-flop 519
and prevents a strobe signal from being generated on conductor 522. After the data bit has been received three times in the same way, the flip
Flop 518 remains in the reset state and conductor 5
No output appears on 21. The clock signal from gate 514 clocks flip-flop 519 to 1.
state and provide a strobe signal on conductor 522 to read data into register 520. If successive bits of the data word are not identical, flip-flop 518 is preset and no strobe signal is generated. FIG. 16 is a table identifying various signals transmitted between a central office location and a remote terminal location using the data transmitter of FIG. 14 and the data receiver of FIG. 15. The three bits thus transmitted to the central office location (identified as D0, D1 and D2) are SEIZE RC, PROCEED
Represents RC and TFSTALM RC signals. In the opposite direction from the central station to the remote terminal, D0 is OH
signal, D1 is PROCEED CR signal, D2 is
TESTALM Represents CR signal. To better understand the automated test sequence performed by the versus gain test controller 26 of FIG. 1, consider the test termination 62 shown in FIG.
Generally, K19 contacts 327 and 328 are terminal circuit 6
2 and the ringing signal detector 329 to switch the remote terminal of the channel. When K19 contacts 327 and 328 are activated, the channel test unit of FIG. It is said to be in a hooked state. In operation, the remote terminal starts with an absorbing termination (contacts 327 and 328 in the restored state) and each time it desires to change termination 62, it generates a new coded ring to establish a new termination. The remote terminal is returned to the on-hook state (contacts 327 and 328 activated) in preparation for receiving signals. K20 contact 334 provides a reflective termination when closed. When these contacts are opened, absorbent terminations are provided by resistors 335 and 336. Chip party identification is provided by K20 contact 340 and K21 contact 341. K20 contact 340 controls the polarity of the chip-to-earth discrimination current;
K21 contact 341 interrupts this current path. The various termination sequences are more clearly shown in the state diagram of FIG. Referring to FIG. 17, initial state 5 of the termination circuit
26 provides an absorbable termination for chip party identification. That is, K19 contacts 327 and 328 are restored, K20 contacts 334 and 340 are also restored, and K21
Contact point 339 is also restored. In this state, measurements for reverberant return loss and monetary channel units are possible. Once these measurements are completed,
The circuit is turned on by an on hook signal transmitted over the data link as shown in Figure 16.
Return to hook state 525. The circuit of FIG. 10 is then ready to receive an encoded ringing signal that repositions the termination. Negative superimposed rigging on the ring conductor, for example, sets up a reflective termination without TPI (see state 527), which can be used to measure round-trip return loss and empty channel noise. Once these measurements are completed, the remote terminal 15
returns to the on-hook state by a signal transmitted on the data link. Similarly, a positive superimposed ringing signal on the ring conductor is terminated at 62 without a chip party identification connection as shown in state 528.
is in the absorption state. After taking measurements in this state, the termination returns to the on-hook state 525 again with an on-hook data command. Similarly, positive superimposed ringing on the chip conductor can be used to place the termination in the absorption state 529 by chip-party identification, or negative superimposed ringing on the chip conductor can be used to identify the chip-party. is used to create a reflective termination state 530. A summary of these states and the signals necessary to assume these states and the three relays 331,
The states of 332 and 333 are shown in the table.

18, 19 and 20 show detailed flow charts of various test sequences controlled by the microprocessor in the vs. gain test controller 26 using the various terminations shown in FIG. There is.
The flow chart of the test series in FIG. 18 is also representative of other test series, so it will be described in detail.
At the beginning of the test, the PROCEED CR signal places the termination in the initial absorption state. That is, as shown in the table, the K19 relay 331 is brought into the restored state, and the K20 relay 332 and the K21 relay 333 are brought into the restored state. In this state, resistors 335 and 336
provides absorbent terminations, K20 contacts 340 and
K21 contact 339 allows a positive coin identification current to flow. Next, the central office tester unit 131
Add a standard -48V battery on the ring conductor,
Ground the chip conductor. This is accomplished by K5 contact 175, which remains in the restored state, and K8 contact 180, which also remains in the restored state, as shown in FIG. Test signal oscillator 163 is then enabled by allowing K10 contact 166 to remain open. This is done in box 600 of FIG. Judgment box 601
The off-hook condition is tested to ensure that all these connections are set up. As shown in FIG. 9, a negative voltage is supplied to the ring conductor from a power source 313 through a normally closed contact 316. The presence of this off-hook voltage causes off-hook current to flow across absorbing resistors 335 and 336.
(Fig. 10), and this line current flows through the current detector 2 in the tester unit 131 (Fig. 6).
02 is allowed to be detected. If no current is detected, this indicates a fault condition as shown in box 603. When an off-hook current is detected, the test tone and detectors 167, 168, 17 of FIG.
0 and 171 measure echo return loss as shown in box 602 of FIG. If this echo return loss is greater than or equal to the threshold set by comparator circuit 171, the test continues. However, if this threshold is exceeded, then a fault condition again exists, as indicated by box 605. If the channel passes this test, +48V is applied to the chip conductor with the ring conductor open, as shown in box 606. A positive voltage on the chip conductor will not cause chip current to flow in the regular subscriber set, but will allow chip current to flow in the money telephone set. In this way, the semi-constant box 607 checks this chip current,
If so, a flag in box 608 is set to indicate that the channel is a money channel. If no chip current flows, the channel is assumed to be a non-monetary channel. In box 609 the termination is again (data
(via the link command), a burst of negative ringing on the ring conductor is sent, and then -48V is applied to the ring conductor with the tip conductor grounded as shown in box 610.
voltage is applied. The termination is again tested in semi-steady box 611 to see if it is on-hook, and if not, a fault indication is given in box 612. If the telephone set is on-hook, it is now possible to measure channel loss. The negative superimposed ringing signal on the ring conductor transmitted by box 609 is
Activating the K20 contact 334 sets the reflective termination state 527 of FIG. In this condition, the test tone is reflected from the shorted reflective termination and the return signal is therefore a measure of the open channel loss. This measurement is made in box 613, which is the same detection circuit 167, 168, 17 of FIG.
0 and 171. Semi-determined box 61
If this channel loss is below a desired threshold, as shown at 4, a fault condition in box 615 is entered. If the threshold is exceeded, test signal oscillator 163 (FIG. 6) is turned off by actuating K10 contact 166, as shown in box 616 of FIG. The open channel noise can be measured in decision box 617 to determine whether the current free channel noise is above or below a desired threshold. To measure the noise signal, use K11 in Figure 6.
Contact 169 is closed to provide an additional gain of 50 dB to the measurement path. If the noise signal is above this threshold, a fault state 618 is entered. If below the threshold, these -48 volts are applied to the chip conductor with the ring conductor open, as shown in box 619. In this condition there should be no chip current. This is tested in decision box 620 and if chip current is detected a fault state 621 is entered. If no chip current is detected, “single
Party OK” check flag is box 62
Set at 2. After that, the judgment box 623
At , it is checked whether the money stock is set. If the currency flag is set, the test proceeds to the currency series shown in box 624 (details are shown in FIG. 19). If the currency flag is not set, proceed to box 625 and enter the multiparty flag in Figure 20.
Enter the test series. The test sequence of FIGS. 19 and 20 is quite similar to the test sequence discussed in connection with FIG. As in FIG. 18, these test sequences use encoded ringing signals or ±
This includes applying a 130V coin voltage or applying a coin or transmit battery voltage to test the particular condition of the subscriber channel formed by the carrier. AC measurements for return loss, open channel loss, and mild state noise are also made as described in connection with FIG. 18. Upon successful completion of all appropriate test series, the subscriber channel is marked OK;
This OK condition is relayed back to the RSB by providing a tone burst or DC voltage level on the RSB trunk 25. A test executor at the RSB can request an indication of the test results at any time after the test is completed. RSB
When automatic test equipment is used in a test system, special voltage levels are used to signal the automatic test equipment that a test has been successfully completed or has not yet completed. It will be appreciated that the paired gain test system described above may be used to simultaneously test both the metal wire drop connected to the subscriber telephone and the subscriber channel formed by the carrier through the paired gain system. . This test system is completely independent of the type of gain versus gain system used. This is because the test system applies standard telephone signals to control the test sequence. In order to perform the necessary tests in this manner, the remote termination of the channel formed in the carrier is controlled using standard multi-party ringing signals or coinage and return signals. An indication is generated at the central office location to alert that a failure has occurred in the test executor's channel which causes the test sequence to fail at any point in the test sequence. The metal wire pair strung between the central office terminal and the remote terminal (pair 28 in FIG. 1) used for testing purposes is shared by all subscribers at the remote location. In this way, only one subscriber in the gain system can be tested at any one time. This is not a major limitation on the test procedure since the automatic channel test can be completed in a few seconds (2-4 seconds). The test executor can re-run the test sequence at any time by restarting the test request. Multiple test units in a gain-to-gain test unit
A single RSB can simultaneously test subscriber channels in different gain systems by providing multiple test trunks simultaneously connected to the gain test controller. Please note that. In general, this ability allows RSB testers to perform tests on any subscriber, regardless of whether the subscriber is being served by a metal wire pair or through a pair-to-gain system. I can do it. This transparency of the test system to the type of subscriber service provides significant savings to the central office repair facility. The tester does not have to learn and become familiar with separate test procedures for different types of subscriber services. Additionally, because much of the testing is done automatically and quickly, test procedures can be executed quickly, thereby speeding up the overall operation of the RSB. The above can be summarized as follows. A test system is shown for telephone subscriber loops formed in part by multiplexing facilities, which have become known as gain-to-gain systems.
In this test equipment, the local drop-in line from the remote terminal of the gain system to the subscriber is separated from the carrier system itself and tested by connecting it to a separate pair of metal wires running from the central office to the remote terminal location. be done. At the same time, the part of the subscriber loop formed by the carrier is connected to automatic test equipment, which tests not only the transmission characteristics of the channel formed by the carrier, but also the ringing of the channel formed by the carrier. The ability to transmit monitoring information such as monetary control and party identification information is also automatically tested. The remote terminals of the gain channels are selectively terminated with reflective or absorptive terminations to aid in these test procedures. The test system is designed so that the channels formed by the carrier appear to the tester at the central office as if they were the same as a metal wire loop, and therefore the supervisor who tests the subscriber loop is The burden on the person above will be significantly reduced.

[Brief explanation of drawings]

1 is a general block diagram of a gain versus gain test system embodying the invention; FIG. 2 is a more detailed block diagram of a test connection for a single subscriber loop using the test equipment of FIG. 1; FIG. 3 is a more detailed block diagram of a central office channel unit useful in the gain-to-gain test system of FIG.
Figure 3 shows a detailed circuit diagram of a ringing signal detector suitable for use in the channel unit of Figure 3; Figure 5 shows a central office test used to perform automatic channel testing in the system of Figure 1. A more detailed block diagram of the control device; FIG. 6 is a detailed circuit diagram of the tester unit in the test control device of FIG. 5; FIG. 7 shows a microprocessor useful as the control circuit of the test control device of FIG. General block diagram of;
8 is a detailed logic circuit diagram of a central office channel test unit useful in the gain-to-gain test system of FIG. 1; FIG. 9 is a detailed logic diagram of a remote terminal channel test unit useful in the gain-to-gain test system of FIG. 10 is a detailed block diagram of a remote terminal channel test unit useful in the gain-to-gain test system of FIG. 1; FIG. 11 is a detailed block diagram of a remote terminal channel test unit useful in the gain vs. FIG. 12 is a detailed circuit diagram of the ringing signal logic used in the unit; FIG. 12 is a detailed schematic of the line feed detection circuit used in the remote terminal channel test unit of FIG. 10; FIG. The figure is the first
A detailed logic diagram of the control circuitry in the remote terminal channel test unit of FIG. 0; FIG. 14 shows both the central office channel test unit of FIG. 8 and the remote terminal channel test unit of FIG. Detailed block diagram of a data transmitter useful in;
FIG. 15 is a detailed block diagram of a data receiver useful in both the central office channel test unit of FIG. 8 and the remote terminal channel test unit of FIG. 10; FIG. 16 is a detailed block diagram of a data receiver useful in both the central office channel test unit of FIG. FIG. 17 represents the sequence of the remote terminal test termination circuit shown in the circuit diagram in FIG. 10; State diagram shown; 1st
8 is a flow chart of the test sequence provided by the microprocessor of FIG. 7 to test a single party carrier channel in the system of FIG. 1; FIG. 19 is a flow chart of the test sequence provided by the microprocessor of FIG. Flow chart of the test sequence for the monetary channel in the system; FIG. 20 is a flow chart of the test sequence for the multiparty channel in the versus gain system of FIG. [Explanation of codes of main parts] Claims code City service line 16 Central office 10

Claims (1)

[Scope of Claims] 1. A subscription realized by a combination of a channel formed by a carrier in at least one gain-to-gain subscriber loop transmission system and a local drop-in line from a remote terminal of the transmission system to a subscriber telephone. In a gain-to-subscriber loop test method for testing subscriber loops, a metal wire signal path from a central office test facility to a remote terminal and means for connecting the subscriber drop-in line to be tested to the remote terminal of the metal wire signal path. drop-in test means for testing a channel formed by a carrier corresponding to the subscriber being tested; and channel testing means for testing the channel formed by the carrier corresponding to the subscriber being tested via a metal wire signal path from the central office test facility to a remote terminal; a gain-to-gain subscriber loop comprising: means for operating said drop line testing means to test a drop line of said subscriber; and means for simultaneously operating said channel testing means to test a channel formed by a carrier corresponding to said subscriber being tested; Test method. 2. The system according to claim 1, wherein a single metal test wire pair is provided between a central office terminal of the transmission system and a remote terminal of the transmission system; and means for sharing the test line pair between all of the subscriber loops. 3. In the system according to claim 1 or 2, a plurality of test trunks extending from the central office test facility to a central office switching facility, and connecting the test facility to the metal wire signal path and connecting the test trunks to the central office switching facility, means in the test trunk for disconnecting the test trunk to connect a switching facility to the channel test means. 4. The method according to claim 1, 2 or 3, wherein the channel test means is an automatic test execution means at a central office terminal of the transmission system, and an automatic test execution means at a remote terminal of the transmission system. A gain-to-gain subscriber loop test scheme including means for selectively terminating channels formed by. 5. The system of claim 4, wherein the automatic test execution means includes a storage program microprocessor. 6. The arrangement according to claim 4 or 5, wherein the selective termination means includes means for changing the termination of the channel formed by the carrier at the remote terminal in response to a telephone supervisory signal. Includes gain-to-subscriber loop test method. 7. In the system according to any one of claims 1 to 6, a data link in the transmission system, and means having the data link for simultaneously operating the drop-in line test means and the channel test means. Gain vs. subscriber loop test method including. 8. The system according to claim 7, comprising test voltage response means provided at a central office terminal of each channel of the transmission system and generating a tone in response to a test voltage from the test facility; a tone detecting means for initiating said simultaneously operating means in response to a gain-to-gain subscriber loop test method. 9. In the method according to any one of claims 1 to 8, a test facility is provided, and a connection is established between the test facility and either a metal wire subscriber loop or a subscriber loop formed by a carrier. and means for disconnecting only subscriber loops formed by carriers. 10. The system according to claim 9, comprising: test voltage detection means associated with the subscriber loop formed by the carrier; and means having the test voltage detection means for energizing the disconnection means. Gain vs. subscriber loop test method including. 11. The method according to any one of claims 4 to 10, wherein the selective termination means comprises means for providing absorbing termination and means for providing reflective termination. method. 12. A system according to any one of claims 4 to 11, wherein the selective termination means comprises means for providing a current path for chip party identification. 13. In the system according to any one of claims 1 to 12, means for testing the alternating current characteristics of a subscriber loop formed by the carrier, and a telephone signal of the subscriber loop formed by the carrier. A gain versus subscriber loop test method comprising automatic carrier channel test equipment consisting of means for testing characteristics. 14. The method according to claim 13, wherein the alternating current testing means comprises a means for testing echo return loss, a means for testing transmission loss, and a means for testing empty channel noise. Subscriber loop test method. 15. A system according to claim 13 or 14, comprising: means for testing single-party and multi-party ringing signaling; and means for testing coin channel monitoring and signaling. A vs. gain subscriber loop test method including test measures.